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<table width="100%" summary="page for toxicity"><tr><td>toxicity</td><td style="text-align: right;">R Documentation</td></tr></table>

<h2>Toxicity of Carboxylic Acids Data</h2>

<h3>Description</h3>

<p>The aim of the experiment was to predict the toxicity of carboxylic acids on
the basis of several molecular descriptors.
</p>


<h3>Usage</h3>

<pre>data(toxicity, package="robustbase")</pre>


<h3>Format</h3>

<p>A data frame with 38 observations on the following 10 variables which are
attributes for carboxylic acids:
</p>

<dl>
<dt><code>toxicity</code></dt><dd><p>aquatic toxicity, defined as
<i>log(IGC50^(-1))</i>; typically the &ldquo;response&rdquo;.</p>
</dd>
<dt><code>logKow</code></dt><dd><p><i>log Kow</i>, the partition coefficient</p>
</dd>
<dt><code>pKa</code></dt><dd><p>pKa: the dissociation constant</p>
</dd>
<dt><code>ELUMO</code></dt><dd><p><b>E</b>nergy of the <b>l</b>owest
<b>u</b>noccupied <b>m</b>olecular <b>o</b>rbital</p>
</dd>
<dt><code>Ecarb</code></dt><dd><p>Electrotopological state of the <b>carb</b>oxylic group</p>
</dd>
<dt><code>Emet</code></dt><dd><p>Electrotopological state of the <b>met</b>hyl group</p>
</dd>
<dt><code>RM</code></dt><dd><p>Molar refractivity</p>
</dd>
<dt><code>IR</code></dt><dd><p>Refraction index</p>
</dd>
<dt><code>Ts</code></dt><dd><p>Surface tension</p>
</dd>
<dt><code>P</code></dt><dd><p>Polarizability</p>
</dd>
</dl>



<h3>Source</h3>

<p>The website accompanying the MMY-book:
<a href="http://www.wiley.com/legacy/wileychi/robust_statistics">http://www.wiley.com/legacy/wileychi/robust_statistics</a>
</p>


<h3>References</h3>

<p>Maguna, F.P., Núñez, M.B., Okulik, N.B. and Castro, E.A. (2003)
Improved QSAR analysis of the toxicity of aliphatic carboxylic acids;
<em>Russian Journal of General Chemistry</em> <b>73</b>, 1792&ndash;1798.
</p>


<h3>Examples</h3>

<pre>
data(toxicity)
summary(toxicity)
plot(toxicity)
plot(toxicity ~ pKa, data = toxicity)

## robustly scale the data (to scale 1) using Qn
(scQ.tox &lt;- sapply(toxicity, Qn))
scTox &lt;- scale(toxicity, center = FALSE, scale = scQ.tox)
csT &lt;- covOGK(scTox, n.iter = 2,
              sigmamu = s_Qn, weight.fn = hard.rejection)
as.dist(round(cov2cor(csT$cov), 2))
</pre>


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